National wikipedias still have to bear English sorting order, which orders the accented characters outside of normal sort which is "not acceptable" for the languages. This problem is most visible in the rise of Categories, but present in every automatic list, like Allpages or the list of registered editors.
I would guess either mySQL or PHP can utilise national locales/collation orders which would simply require the sites to specify their locale and there we go. Or do I guess it wrong? (I am only familiar with perl and postgres, where this works.)